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PubMed1984

[Melanoma and dysplastic nevus after 8 years of topical Caryolysine].

A 48-year-old woman with poikiloderma atrophicans vasculare was treated with topical mechlorethamine, applied three times weekly, for eight years. After five years treatment she developed nine melanocytic naevi on covered skin. The naevi spread for the next three years and a surgical excision was performed. Pathological examination revealed one level II SSM, one level I SSM and seven junctional naevi with focal dysplasia or melanocytic hyperplasia. The development of melanoma and dysplastic naevi after topical mechlorethamine has not been previously reported. However it seems likely that mechlorethamine was the causative agent. As for the mechlorethamine's imputability in this case, we have used a method combining intrinsic identification of adverse drug responsibility's score, based on the clinical case and on extrinsic identification based on literature evaluation. We suggest that mechlorethamine could act as UV light.

Administration, Topical↗
PubMed1995

Sizing highly fragmented DNA in individual apoptotic cells using the comet assay and a DNA crosslinking agent.

TK6 human B lymphoblast cells exposed to ionizing radiation undergo apoptosis in a time and dose-dependent manner. The resulting highly fragmented DNA is easily detected using the comet assay, a sensitive microscopic gel electrophoresis method capable of measuring DNA strand breaks in individual cells. The degree of DNA fragmentation may be indicative of different stages in the fragmentation process, responses to different agents, and/or cell type-dependent differences. In an effort to determine the number of breaks present in each apoptotic cell, we first applied a DNA-crosslinking agent, mechlorethamine, to TK6 cells containing a known number of DNA double-strand breaks produced by X rays. As the concentration of mechlorethamine increased, crosslinked DNA was less able to migrate during gel electrophoresis. Exposure of TK6 cells to 5 microM mechlorethamine prior to irradiation with 20 Gy was sufficient to "hide" the presence of these breaks by preventing DNA from migrating during electrophoresis. However, in apoptotic TK6 cells, it was necessary to apply a dose of mechlorethamine several times higher in order to produce a similar degree of inhibition of DNA migration. Calibrations using either the alkaline or neutral comet assays indicate that the average DNA fragment size in apoptotic TK6 cells is about 50 kb. Even in cells containing only 10-20% of the original amount of DNA, the remaining fragments still averaged about 50 kb, indicating that fragmentation to much smaller sizes occurs in some parts of the genome before others. When Chinese hamster V79 cells were exposed to hyperthermia (45 degrees C for 20 min), necrosis was induced over a period of several days. The size of DNA fragments in these cells was considerably larger (200-400 kb) and heterogeneity in appearance of comets was larger than observed for TK6 cells. This crosslinking method may be useful in discriminating cells dying by apoptosis from cells damaged or dying by other mechanisms.

Animals↗
PubMed1994

Decrease in penbutolol protein binding as a consequence of treatment with some alkylating agents.

The effect of in vitro treatment of serum with the alkylating agents carmustine (BCNU) and mechlorethamine on the protein binding of penbutolol, a basic agent mainly bound to alpha 1-acid glycoprotein (AAG), was investigated. The free fraction of penbutolol increased significantly (P < 0.001) after the treatment of serum with BCNU (5.27+ +/- 0.47%) and with mechlorethamine (5.23% +/- 0.17%), being 1.98% +/- 0.18% in serum not treated with BCNU or mechlorethamine. In addition, after incubation with BCNU (2 h), the free fraction of penbutolol continued increasing (10.96% +/- 0.70% vs 5.27% +/- 0.47% at time 0; P < 0.001), whereas it remained unchanged after incubation with mechlorethamine. Moreover, dialysis against saline for 24 h did not restore the free fraction of penbutolol, which increased after treatment with carmustine (9.05% +/- 1.24% vs. 11.04% +/- 1.55%, nondialyzed). We concluded that the treatment of cancer patients with alkylating agents could alter the serum proteins and modify their binding capacity, and this should be taken into account in the simultaneous treatment of these patients with other basic drugs like penbutolol, e.g., methadone.

Adult↗
PubMed2004

Adenine-containing DNA-DNA cross-links of antitumor nitrogen mustards.

Nitrogen mustards (NMs) are useful chemotherapeutic agents in the treatment of lymphoma, leukemia, multiple myeloma, and ovarian carcinoma. The antitumor activity of NMs has been attributed to their ability to cross-link the twin strands of DNA. The resulting bifunctional lesions, if not repaired, can inhibit DNA replication and transcription, eventually leading to cell cycle arrest, apoptosis, and the inhibition of tumor growth. The predominant bifunctional DNA lesions of NM have been reported to involve the distal guanine bases in the opposite strands of 5'-GNC sequences. In the present work, the formation of guanine-adenine and adenine-adenine adducts of N,N-bis(2-chloroethyl)methylamine (mechlorethamine) in double-stranded DNA is demonstrated. Guanine-adenine cross-links of mechlorethamine were identified as N-(2-[N3-adenyl]ethyl)-N-(2-[N7-guanyl]ethyl)methylamine (N3A-N7G-EMA), N-(2-[N1-adenyl]ethyl)-N-(2-[N7-guanyl]ethyl)methylamine, and N-(2-[N(6)-adenyl]ethyl)-N-(2-[N7-guanyl]ethyl)methylamine. All three adducts were produced interstrand, while N3A-N7G-EMA was the dominant intrastrand G-A cross-link. The prevalent adenine-adenine mechlorethamine lesions have the structure of N,N-bis(2-[N3-adenyl]ethyl)methylamine (bis-N3A-EMA). DNA-derived lesions have the same HPLC retention times, UV spectra, and MS/MS fragmentation patterns as the authentic standards prepared independently. bis-N3A-EMA lesions were produced in a concentration-dependent manner in calf thymus DNA treated with increasing amounts of mechlorethamine. Furthermore, HPLC-ESI-MS/MS analysis was used to demonstrate the formation of analogous N3-N3 adenine lesions in DNA treated with aromatic nitrogen mustards, N,N-bis(2-chloroethyl)-p-aminophenylbutyric acid and L-phenylalanine mustard. The presence of cross-linked adenine-adenine lesions may explain the enhanced cytotoxicity and mutagenicity of NMs in cells deficient in N3-alkyladenine glycosylase.

Adenine↗
PubMed1989

Influence of granulocytopenia on canine cerebral ischemia induced by air embolism.

We subjected nine dogs with severe granulocytopenia 4 days after the administration of mechlorethamine to 1 hour of cerebral ischemia induced by the controlled, incremental injection of air into the internal carotid artery. Cortical somatosensory evoked responses and cerebral blood flow determined by [14C]iodoantipyrine autoradiography were compared with those of six control dogs that had received mechlorethamine 1 day previously and were not yet granulocytopenic. Eleven additional control dogs received no mechlorethamine but had identical ischemic insults and were followed for 4 hours after ischemia. Both control groups had identical evoked response outcomes after 1 hour of recovery from ischemia. Granulocytopenic dogs had improved evoked response recoveries compared with either control group after 1 hour of recovery. No areas of very low blood flow were observed 1 hour after ischemia in the granulocytopenic dogs, but three of five dogs in the control group receiving mechlorethamine had such areas.

Agranulocytosis↗
PubMed1994

Long-term topical nitrogen mustard treatment does not induce pulmonary fibrosis in MF patients.

Eleven patients with mycosis fungoides had X-ray examinations of their lungs before, during and after topical treatment with mechlorethamine. The mean number of treatments was 163, ranging from 28 to 300 treatments within a period of 1 to 13 years (mean 7.8 years). Each exposure to the skin of mechlorethamine was between 20 and 40 mg giving a cumulative dosage in the range from 1.120 mg to a maximum of 12.000 mg. We looked for potential lung damage from mechlorethamine vapours, such as fibrosis of the lungs, but found none. Thus, we conclude that topical treatment with mechlorethamine of patients with mycosis fungoides is not only an effective treatment, but also a safe therapy.

Administration, Cutaneous↗
PubMed1987

Reduced levels of drug-induced DNA cross-linking in nitrogen mustard-resistant Chinese hamster ovary cells expressing elevated glutathione S-transferase activity.

We have reported previously (C. N. Robson et al., Cancer Res., 46: 6290-6294, 1986) the isolation of a Chinese hamster ovary cell line, designated CHO-Chlr, that exhibits resistance to bifunctional nitrogen mustards while maintaining the normal parental level of sensitivity to several other alkylating agents. We have compared the rate of formation and repair of DNA cross-links induced by mechlorethamine in CHO-Chlr and parental CHO-K1 cells, both in intact cells and in isolated nuclei. Equimolar doses of mechlorethamine induce significantly fewer DNA interstrand cross-links in CHO-Chlr cells than in CHO-K1 cells, but levels of DNA-protein adducts are approximately equivalent in the two lines. There is a correlation between the relative resistance of CHO-Chlr cells to mechlorethamine (34-fold) and the amount of drug required to induce approximately equal numbers of DNA interstrand cross-links in the two cell lines. This strongly implicates DNA-DNA adducts in the cytotoxic action of mechlorethamine. DNA cross-linking studies on isolated nuclei reveal only minor differences between the two lines even with identical drug treatments. The rate of cross-link repair is comparable in the two cell lines. These results, taken together with our earlier observation that the rate of drug accumulation is identical in these two lines, suggest that enhanced cytoplasmic drug detoxification is the underlying resistance mechanism in CHO-Chlr cells. We have measured cellular glutathione S-transferase activity, using both the general substrate 1-chloro-2,4-dinitrobenzene, and substrates with some specificity for the different classes of transferase isoenzymes. Total enzyme activity (as measured with 1-chloro-2,4-dinitrobenzene) is elevated 3-fold in the resistant cells. A 2- and 5-fold increase, respectively, in activity against ethacrynic acid and cumene hydroperoxide is detectable in CHO-Chlr cells. This elevation in catalytic activity in the resistant cells is reflected in higher levels of both the Yf- and Ya-type transferase subunits.

Animals↗
PubMed1995

Malignant melanoma and other second cutaneous malignancies in cutaneous T-cell lymphoma. The influence of additional therapy after total skin electron beam radiation.

BACKGROUND: Previous large studies have shown that patients with cutaneous T-cell lymphoma are at increased risk for basal cell carcinoma and squamous cell carcinoma, and anecdotal case reports have suggested an association with malignant melanoma. It has been postulated that the exposure of cutaneous structures to potentially carcinogenic therapies, such as ionizing radiation or alkylating agents, might be causally associated with the development of these second cutaneous malignancies, but, to date, no study has directly addressed this issue. The purpose of this study was to evaluate the occurrence of second cutaneous malignancies in a group of patients with cutaneous T-cell lymphoma treated with total skin electron beam therapy and to examine the additional effects of oral psoralen with UV-A phototherapy, topical mechlorethamine hydrochloride therapy, and further radiation therapy. One hundred sixty-four patients with cutaneous T-cell lymphoma who had received total skin electron beam therapy between 1974 and 1990 were identified, and information was abstracted from their records. RESULTS: Six patients developed malignant melanoma 12 to 95 months after total skin electron beam therapy. Of the six patients, three had received oral psoralen with UV-A as additional therapy and two had received topical mechlorethamine. None had received additional radiation therapy. Twenty-four patients developed more than 37 basal cell carcinomas and 34 squamous cell carcinomas from 11 months to more than 10 years after total skin electron beam therapy. Of the 24 patients, 15 had received oral psoralen with UV-A and 12 had received mechlorethamine as additional therapy. Additional radiation therapy had been administered to nine patients. During a median follow-up of 6 years, no patients died of any second cutaneous malignancy. CONCLUSION: We found a high rate of both melanoma and nonmelanoma skin cancer. The additional use of mechlorethamine or oral psoralen plus UV-A, but not radiation, was significantly associated with the development of basal cell carcinoma and squamous cell carcinoma, but not malignant melanoma.

Adult↗
PubMed1999

Clinical characteristics and long-term outcome of patients with generalized patch and/or plaque (T2) mycosis fungoides.

OBJECTIVES: To study the long-term results of treatment of patients with generalized patch and/or plaque mycosis fungoides and to identify clinical characteristics predictive of survival and response to treatment. DESIGN: A single-center, 35.5-year retrospective cohort analysis. SETTING: Private referral medical center. PATIENTS: One hundred seventy-six patients with generalized patch and/or plaque (T2) mycosis fungoides. MAIN OUTCOME MEASURES: Long-term actuarial survival and freedom-from-relapse results as calculated by the Kaplan-Meier method. RESULTS: The long-term (35.5-year) survival of patients with T2 mycosis fungoides is worse than the expected survival of a race-, age-, and sex-matched control population (P<.001). The median survival of the T2 group is 11.7 years. Patients younger than 58 years (median age) at presentation have a more favorable overall and disease-specific survival than the patients who are 58 years or older (P<.001 vs P<.025). Patient sex or race had no significant effect on overall survival. Patients who presented with palpable clinically significant lymph nodes (stage IIA) had long-term survival results similar to those without lymphadenopathy (stage IB), despite improved freedom-from-relapse outcome for patients with stage IB. Twenty-four percent of patients who progressed to more advanced disease had a lower complete response rate to initial therapy than did other patients (21% vs 65%) (P<.001). Patients who received total skin electron beam therapy had a better complete response rate than patients treated with topical mechlorethamine hydrochloride alone; the relapse-free results were superior in patients with a total dose of 30 Gy or higher and in patients who received topical mechlorethamine as adjuvant therapy following total skin electron beam therapy. Despite differences in freedom-from-relapse results among different treatment groups, long-term overall or disease-specific survivals were not significantly different. CONCLUSIONS: A significant proportion (24%) of patients with generalized patch and/or plaque (T2) mycosis fungoides experience disease progression to a more advanced clinical stage, and nearly 20% eventually die of the disease. Younger patients have a more favorable disease-specific long-term outcome than patients who are older. Presence of lymphadenopathy (stage IIA) at diagnosis does not predict worse long-term survival outcome. Clinical features predictive of disease progression include initial lymphadenopathy (stage IIA) and lack of complete response to initial treatment. Despite superior complete response rate to a 30-Gy or higher dose of total skin electron beam therapy, topical mechlorethamine proves to be a cost-effective initial treatment for patients with T2 disease. The concept of an adjuvant therapy after irradiation is appealing, although it may not lead to improved long-term survival.

Adult↗
PubMed1994

Nitrobenzyl mustard quaternary salts: a new class of hypoxia-selective cytotoxins capable of releasing diffusible cytotoxins on bioreduction.

PURPOSE: To explore the utility of a new class of compounds, nitrobenzyl mustard quaternary salts, as hypoxia-selective prodrugs of diffusible cytotoxins. METHODS AND MATERIALS: The parent compound N,N-bis(2-chloroethyl)-N-methyl-N-(2-nitrobenzyl)ammonium chloride (SN 25246) was prepared by reaction of 2-nitrobenzyl chloride with N-methyldiethanolamine, and reaction of the resulting quaternary diol with thionyl chloride at room temperature. The rate of release of mechlorethamine from this compound in the presence of cells under aerobic and hypoxic conditions was determined by trapping with diethyldithiocarbamate. Cytotoxicity was assessed by clonogenic assay of stirred suspension cultures of EMT6 cells, and also in intact and dissociated EMT6 spheroids. In vivo activity was evaluated in mice bearing SC KHT tumors. RESULTS: The parent compound is a stable, water-soluble compound with an E(1) of -369 mV. It releases mechlorethamine, and shows selective toxicity towards hypoxic EMT6 cells in culture, increasing with time to several 1000-fold after 4 h. It is much more active against intact than dissociated EMT6 spheroids, and shows low but statistically significant activity against KHT tumors in vivo. CONCLUSION: Nitrobenzyl mustard quaternary salts are a new class of hypoxia-selective cytotoxin. The parent compound shows very high selectivity for hypoxic cells in vitro, and undergoes reduction in hypoxic cells, releasing mechlorethamine which can back-diffuse to kill surrounding oxygenated cells.

Animals↗
PubMed1992

Use of [8-3H]guanine-labeled deoxyribonucleic acid to study alkylating agent reaction kinetics and stability.

Alkylation at the N7 position of guanine in DNA renders the C8-hydrogen acidic. This serves as the basis for an assay of guanine N7 alkylation using [8-3H]-guanine-labeled DNA. I modified the assay by preparing a high specific activity substrate in vitro and by replacing the distillation step with charcoal adsorption of substrate. Using the appearance of noncharcoal-adsorbable label as a measure of guanine-N7 alkylation I examined the reaction of DNA with dimethyl sulfate and mechlorethamine. The rate of reaction of dimethyl sulfate with the N7 position of guanine in DNA was constant over time, i.e., loss of label from DNA proceeded linearly with time. On the other hand, the rate of reaction of mechlorethamine with DNA increased with time, consistent with the initial formation of the reactive aziridinium ion. The assay can also be used to compare the reaction rates of various alkylating agents with DNA. Thus, the acridine mustards ICR-170 and quinacrine mustard were far more potent alkylating agents than mechlorethamine. Furthermore the assay may be used to determine the alkylating potency and stability of various alkylating agent preparations: while frozen solutions of acridine mustards in organic solvents retained alkylating activity for several months, different commercial preparations of quinacrine mustard had little or no alkylating activity.

Alkylating Agents↗
PubMed1997

Specificity and kinetics of interstrand and intrastrand bifunctional alkylation by nitrogen mustards at a G-G-C sequence.

Previous work showed that melphalan-induced mutations in the aprt gene of CHO cells are primarily transversions and occur preferentially at G-G-C sequences, which are potential sites for various bifunctional alkylations involving guanine N-7. To identify the DNA lesion(s) which may be responsible for these mutations, an end-labeled DNA duplex containing a frequent site of melphalan-induced mutation in the aprt gene was treated with melphalan, mechlorethamine or phosphoramide mustard. The sequence specificity and kinetics of formation of both interstrand and intrastrand crosslinks were determined. All mustards selectively formed two base-staggered interstrand crosslinks between the 5'G and the G opposite C in the 5'G-G-C sequence. Secondary alkylation was much slower for melphalan than for the other mustards and the resulting crosslink was more stable. Mechlorethamine and phosphoramide mustard induced intrastrand crosslinks between the two contiguous Gs in the G-G-C sequence in double-stranded DNA, but melphalan did not. Molecular dynamic simulations provided a structural explanation for this difference, in that the monofunctionally bound intermediates of mechlorethamine and phosphoramide mustard assumed thermodynamically stable conformations with the second arm in a position appropriate for intrastrand crosslink formation, while the corresponding melphalan monoadduct did not.

Adenine Phosphoribosyltransferase↗
PubMed2006

MOPPEBVCAD chemotherapy with limited and conditioned radiotherapy in advanced Hodgkin's lymphoma: 10-year results, late toxicity, and second tumors.

PURPOSE: MOPPEBVCAD (mechlorethamine, vincristine, procarbazine, prednisone, epidoxirubicin, bleomycin, vinblastine, lomustine, doxorubicin, and vindesine) chemotherapy with limited radiotherapy was devised in 1987 to reduce late toxicity and second tumor incidence while trying to improve effectiveness through increases of dose intensity and dose density. Late results, toxicity, and second tumor incidence were reviewed in all the patients treated. EXPERIMENTAL DESIGN: The drugs of three previous alternating regimens [CAD (lomustine, melphalan, and vindesine), MOPP (mechlorethamine, vincristine, procarbazine, and prednisone), and ABV (doxorubicin, bleomycin, and vinblastine)] were intensified and hybridized, the cumulative dose of mechlorethamine was lowered, and irradiation was delivered to no more than two sites either bulky or partially responding to chemotherapy. RESULTS: A total of 307 previously untreated advanced-stage patients underwent MOPPEBVCAD chemotherapy. Radiotherapy was delivered to 118 of 307 patients (38%). Remission was complete in 290 patients (94%). With a median follow-up of 114 months, 10-year overall, disease-free, and failure-free survival rates were 79%, 84%, and 71%, respectively. Forty-two patients relapsed and 60 died. The causes of death were Hodgkin's lymphoma in 36 patients, second neoplasms in 12, cardiorespiratory diseases in 4, pulmonary diseases in 2, and unknown in 6. Sixteen second tumors (of which nine were myelodysplasia and/or acute leukemia) were diagnosed in all. Outside this series of 307 patients, MOPPEBVCAD obtained complete responses in 12 of 15 relapsed and 9 of 9 refractory patients who had previously been treated with other regimens. CONCLUSIONS: Clinical response and long-term results are very satisfactory, whereas the second tumor incidence was lower than would have been expected with MOPP analogues. Given its response/late toxicity balance, MOPPEBVCAD does not undermine the leading role of ABVD as first-line regimen but can be indicated as a very effective second-line conventional therapy.

Adolescent↗
PubMed1994

Leukemia risk following Hodgkin's disease: relation to cumulative dose of alkylating agents, treatment with teniposide combinations, number of episodes of chemotherapy, and bone marrow damage.

PURPOSE: The development of leukemia is one of the most serious long-term complications of modern treatment for Hodgkin's disease (HD). This study was undertaken to examine the relation between risk of leukemia and various treatment factors (including cumulative dose of cytostatic drugs and interaction with radiotherapy [RT]), while also assessing the effect of treatment-induced bone marrow damage. PATIENTS AND METHODS: We conducted a case-control study in a cohort of 1,939 patients treated for HD between 1966 and 1986 in the Netherlands. Detailed information from the medical records was obtained for 44 cases of leukemia and 124 matched controls, in whom leukemia had not developed. RESULTS: The cumulative dose of mechlorethamine was the most important factor in determining leukemia risk. As compared with patients who received RT alone, patients treated with six or fewer cycles of combinations including nitrogen mustard (mechlorethamine) and procarbazine had an eightfold increased risk of developing leukemia (P = .08), while patients who received more than six of such cycles had a greater than 40-fold excess risk (P < .001). Treatment with lomustine or a combination of teniposide and cyclophosphamide also significantly increased the risk of leukemia. Patients who had received chemotherapy (CT) during two or more time periods had a nearly 40-fold increased risk of leukemia as compared with patients treated only once. The extent of RT did not further increase leukemia risk among patients who also received CT. A significantly increased risk of leukemia was found among patients with low platelet counts, both in response to initial therapy and during follow-up. Patients who experienced 2 or more half-year periods with platelet counts less than 75 x 10(6)/mL had an approximately fivefold risk of developing leukemia, and a similar risk increase was found for patients who responded to initial treatment with a > or = 70% decrease of platelet counts (as compared with patients who had a < or = 50% decrease). CONCLUSION: In addition to mechlorethamine, lomustine and teniposide combinations were also linked to an elevated risk of developing leukemia. Since the number of CT episodes was found to be a strong determinant of leukemia risk, it is important that new therapies for HD continue to yield high initial cure rates. Further studies are warranted to investigate whether patients at high risk for developing leukemia may be identified from the response of their platelets to initial therapy for HD.

Adult↗
PubMedDate not supplied

[Value of chlormethine in children with corticoid-dependent or partially corticoid-sensitive nephrosis, in steroid poisoning].

Mechlorethamine was administered at a low dose (0.8 mg/kg) to 27 children presenting with steroid dependent or partially responsive nephrotic syndrome, with signs of steroid toxicity. This drug induced a fast decrease of proteinuria (average delay: 7 days). It led to long lasting remission (average follow-up 34 months) in 16 cases (59%). Relapse occurred in 11 children (41%) most often (9 of 11 cases) in the first 7 months. However the evolutive pattern was clearly improved in 5 of these cases. Altogether, mechlorethamine allowed to stop corticosteroid therapy or, at least, to reduce the given dose, with a decrease of the signs of steroid toxicity, in 78% of the cases. In 6 cases (22%) evolution was almost not improved. One may hope that this dosage of mechlorethamine will not be gonadotoxic. This should be checked later on.

Adolescent↗
PubMed1982

[Inhibitory effect of antineoplastic agents on human cholinesterases].

Human motor endplate acetylcholinesterase was inhibited in vitro by alkylating antineoplastic agents, most strongly by mechlorethamine, followed by DTIC, ACNU, cyclophosphamide and ifosfamide. Eleven other antineoplastic agents did not inhibit the enzyme substantially nor interfered with cholinesterase measurement. Cyclophosphamide and mechlorethamine inhibited human plasma pseudocholinesterase most strongly, followed by thiotepa, ACNU, DTIC, ifosfamide and BCNU. Mechlorethamine, ACNU and ifosfamide inhibited the motor endplate and plasma cholinesterase practically equally, DTIC inhibited motor endplate cholinesterase more strongly, while cyclophosphamide was a more selective inhibitor of plasma cholinesterase. Inhibition of human red blood cell acetylcholinesterase was identical to that of motor endplate acetylcholinesterase; therefore, red cells would be a preferable indicator in monitoring cholinesterase inhibition by antineoplastic agents.

Acetylcholinesterase↗
PubMed1995

DNA damage in cyclophosphamide-resistant tumor cells: the role of glutathione.

The relationship between DNA damage removal and cellular sensitivity to the alkylating agent cyclophosphamide (CP), currently one of the most effective drugs in the treatment of human tumors, has not been well established. In the present study, we have analyzed drug-induced DNA cross-link persistence in the CP-resistant subline KHT-rep/iv and its sensitive counterpart KHT-iv. The alkaline elution technique was used to detect both DNA-DNA and DNA-protein cross-links formed following exposure to clinically achievable CP concentrations. In addition, the role of glutathione (GSH) in the cross-link persistence was analyzed. The KHT-rep/iv cell line was chosen for study because compared to the parent KHT-iv line, this cell line demonstrates 2-3-fold increased GSH levels, and resistance to CP is known to be mediated by thiols. Following exposure to 4-hydroperoxy-cyclophosphamide (4-OOHCP), an active form of CP, the KHT-rep/iv cells exhibited fewer total cross-links and a shift in the time of maximal cross-link formation (6.2 at 2 h versus 2.9 at 4 h for the parent and resistant lines, respectively). When the GSH content of the resistant cells was reduced to equal that of the parent cell line prior to the alkaline elution assay, both the total number and time course of development of cross-links were similar between the two lines. Also, when the cells were exposed to mechlorethamine, an alkylating agent which forms cross-links at a much faster rate than 4-OOHCP, the time course of cross-link formation after mechlorethamine exposure was similar between the two sublines, with maximal cross-link formation occurring after a 1-h incubation. The present findings suggest that (a) the increased GSH levels in KHT-rcp/iv cells may be responsible for the delay in maximal cross-link development after treatment with 4-OOHCP, possibly by binding with the monoadduct produced by the drug; and (b) the faster reaction rate of mechlorethamine cross-link formation may prevent the tripeptide from binding to the monoadduct. These results are consistent with the hypothesis that GSH may "quench" the formation of cross-links following 4-OOHCP exposure.

Cell Division↗
PubMed1977

Topical chemotherapy and immunotherapy of mycosis fungoides: intermediate-term results.

A group of 220 patients with mycosis fungoides (MF) and other lymphomatous diseases was treated with sustained topical applications of dilute aqueous solutions of mechlorethamine hydrochloride for intervals ranging in excess of seven years. Response to treatment, immunologic responsiveness, and subsequent course and survival were inversely related to magnitude of disease at time of starting treatment. Relapses were common and in most instances were related to failure to maintenance of topical therapy rather than to drug resistance. In selected patients topical therapy with an analog of mechlorethamine (nor-mechlorethamine) and with topical immunogenic agents provided additional improvement.

Administration, Topical↗